Growth of CdS heterojunctions on Cd0.9Zn0.1Te single crystals with H2S

Polished Cd0.9Zn0.1Te (CZT) single crystals have been exposed to dilute H2S in nitrogen at temperatures from 200 to 280 °C in order to produce a sulfide layer on the surface. The composition of the CZT surfaces before and after H2S exposure has been investigated by photoemission, x-ray absorption, cross-sectional SEM, and spectroscopic ellipsometry. At the highest temperature, H2S exposure removes surface oxides and depletes Te, leaving a CdS surface layer. CdS layers 60 nm thick have been grown with a 2 h exposure to H2S at 280 °C. Surfaces that are initially oxidized through ozone exposure are much more reactive with H2S than unintentionally oxidized surfaces.